2pcs Automatic Infrared Beam Detector Ir Alarm Sensor Door Light Sensor Burglar Alarm System 2Pcs Infrared Beam Detector Burglar Ir Alarm Sensor Automatic Door Light Sensor Alarm System Features Single beam infrared radiation: suitable for anti-theft such as doors and windows, box, fence and so on. Small size, big effect Sealed shell, stronger waterproof: Thanks to the good waterproof design, it can effectively cope with all kinds of bad weather, so that the internal components are not eroded by rain Detection distance 20m: Install to ensure that the emitter and the receiver are on the same horizontal line Stable and reliable anti-interference: using hemispherical optical lens, the beam is concentrated, precise and non-scattering, and the automatic strong light adjustment system can effectively avoid the interference of strong light and car headlights Specifications Light source mode: infrared pulse type Detection method: Beam interruption pick-up type Package Include:2Pcs X Doorbell Note: Due to different personal measurement methods, there will be an error of 2-4 cm, please understand Thanks for your support